PLEASE DO THIS
From working with the FTC on other privacy issues,
it takes a certain amount of momentum for them to actually take this seriously.
(instead of just "playing" at an investigation)
A good number is 10,000+ complaints
Place a prominent link on your websites for your visitors to complain as well.
That's the easiest way for the FTC to actually investigate out of
VERIFIABLE PUBLIC CONCERN instead of a rubberstamped investigation.